Rock-drilling mechanism



June 3, 1930. T. R. E. RUNDQVEST 1,761,313

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Patented June 3, 1930 PATENT OFFICE THORE R. E. RUNDQVIST, OF CLAREMON'I, NEW HAMPSHIRE, ASSIGNOR TO SULLIVAN MACHINERY COMIANY, A COBLPORATION OF MASSACHUSETTS ROCK-DRILLING MECHANISM Application filed May 23,

My invention relates to rock drilling mechanisms and more particularly to an improved rock drill mechanism of the hammer type having an improved fluid actuated motor therefor.

In modern mining and quarrying the constant demand is for greater speed and in response to this demand the designers of rock drilling motors are constantly seeking to produce machines capable'of drilling more rapidly. In this effort they resort to the employment of comparatively heavy hammer pistons which impart a series of impact blows to a drill steel loosely supported in position to be struck by the piston. Furthermore, in the endeavor to improve the fluid distribution means to increase the piston velocity, admission to the front end of the cylinder is delayed to give the piston a substantially uncushioned impact blow on the shank of the steel. The presence of the striking bar diminishes the cushioning area and makes higher cushion pressures essential when needed. This factor, together with delayed admission and leakage, gives rise to possibility of serious damage, when, as during the effort to loosen or withdraw a stuck drill steel from a hole, at which time the shank of the steel moves out of the range of the piston, the cushioning action at the front end of the cylinder may be so slight as to permit the piston to excessively hammer the front cylinder head before the pressure in the cushioning space builds up suliiciently to restrain the piston movement. I

Among the objects of the present invention are the provision of means for preventing the excessive hammering of the front head of the cylinder by the hammer piston, which means are normally inoperative but become auto matically operative upon occasion to prevent breakage of the motor parts. A still further object of my invention is to provide improved means operated by the cushioning pressure in the motor cylinder for admitting an auxiliary supply of live pressure fluid to one end of the automatic fluid distributing valve prior to the admission of throwing pressure thereto and the throwing action thereof on the rel-ye, thereby accelerating the move== 1925. Serial No. 32,462

ment of the valve and consequently retarding the forward movement of the piston, thus preventing the latter from excessively striking the front cylinder head, eliminating resultant damage to the motor parts. A still further object of my invention is to provide improved hole cleansing means for a rock drilling mechanism associated with my improved auxiliary valve. These and other ob jccts and advantages of my invention will, however, hereinafter more fully appear.

My invention, broadly stated, consists of improved means for preventing the hammer piston from excessively striking the front cylinder head during withdrawal of a stuck drill steel from the hole. More specifically, this improved means comprises an auxiliary valve, operated by the relatively high cushioning pressure for the hammer piston at the forward end of the cylinder, for admitting an auxiliary supply of live pressure fluid to the throwing passage for the automatic fluid distributing valve giving this throwing passage a preliminary filling of live pressure fluid prior to the admission of throwing pressure thereto and the throwing action thereof on the valve, consequently accelerating the throwing action of the valve and retarding or shortening the forward stroke of the piston, thus preventing the latter from excessively hammering on the front cylinder head. When normal drilling is resumed the cushioning pressure at the forward end of the cylinder is substantially reduced and the auxiliary valve is rendered inoperative at this time.

In the accompanying drawings I have shown for purposes of illustration one form which my invention may assume in practice.

In these drawings,

Fig. 1 is a diagrammatic longitudinally extending vertical sectional view through a fluid actuated percussive motor with which my improvement is incorporated.

Fig. 2 is a view similar to Fig. l with the valves and the hammer piston in different positions.

F igi 3 is a central longitudinal vertical sectional view taken through the inward earl improved r'lrillingf mechanism;

Fig. 4 is an enlarged detail sectional view of my improved controlling valve illustrating the position thereof when effecting a hole cleansing operation.

In this illustrative embodiment of my invention I have shown a drilling motor generally designated 1 comprising a cylinder 2 having a bore 3 within which a hammer piston 4 is reciprocable. The hammer piston 4 is provided with a forwardly extending striking bar 5 having longitudinally extending flutes or grooves 5 formed therein and is adapted to impart a series of impact blows to the shank of a drill steel 6 supported within a chuck bushing 7 carried by a chuck sleeve 8 mounted within a chuck housing 9 suitably secured to the forward end of the cylinder 2. As illustrated, the steel is mounted for a limited longitudinal movement within a usual steel locking member 10 likewise disposed within the chuck housing 9.

It will herein be observed that for the purpose of causing reciprocation of the piston suitable fluid distribution passages 11 and 12 lead to points contiguous to the opposite ends of the cylinder, the passage 11 leading to the front end of the cylinder, while the passage 12 leads to the rear end thereof. The supply and exhaust of motive fluid through the distribution passages 11 and 12 is controlled by an automatic valve mechanism, generally indicated by 13 and comprising a casing or chest'14 in which a chamber is formed having end bores 15 and an enlarged central bore 16. As illustrated, the passages 11 and 12 communicate with the valve chamber adjacent the ends of the central enlarged bore 16, the passage 11 communicating therewith, as at 17, and the passage 12 communicating therewith, as at 18. Adjacent the remote ends of the smaller bores 15, are ports 19 and 20 connecting throwing passages 21 and 22 with the valve chamber, these passages at their opposite ends communicating with the bore of the cylinder 2 by suitable longitudinally spaced ports 23 and 24, the passage 23 communicating with the cylinder at a point spaced a relatively short distance from the position of the rear end of the piston when the latter is in its steel engaging position, while the port 24 is spaced a substantial distance nearer the front end of-the cylinder, and'so disposed as to form a cushion chamber 25 for the piston 4. Intermediate the ports 17 and 19 and 18 and20, respectively, in the valve casing there are formed suitable exhaust ports 26 and 27'. As shown, within the valve casing 14 is a valve of the well known three-spool type, generally designated 28-, and comprising end spools 29 and 30 fitting the hores 15 and an enlarged central spool 31 fitting the bore 16, the spools 29 and 30 being connected, respectively, with the spool 31 by reduced portions 32. The ends of .the end spools 29 and 30 are recessed,-as at 33, and buffers 34 limit the movements of the valve, these bufiers extending into the recesses 33. A pressure fluid supply port 35 communicates with the enlarged central bore 16 in the central part of the valve chest.

In my improved construction it will herein be observed that I have provided a relatively small restricted passage 37 communicating with the cushioning space 25 at the extreme forward end of the cylinder and the opposite end of this passage 37 communicates with a bore 38 formed within the cylinder 2. As illustrated, disposed within the bore 38 is an auxiliary valve, generally designated 39, comprising end spools 40 and an intermediate grooved portion 41 which communicates, by means of radial ports 42, with a central longitudinally extending aperture 43 formed in the valve. The end of the bore 38 opposite from the end with which the passage 37 communicates, is connected, by means of a passage 44 with the fluid supply port 35. Furthermore, it will be observed that a passage 45 connects the throwing passa e 21 wi h the bore 38 intermediate the ends of the latter.

In the operation of the mechanism above described, it will herein he noted that when the piston 4 is in the position shown in Fig. 1, that is with the valve 28 with its right hand spool 30 in a position against the forward buffer 34, motive fluid is passing from the inlet port 35 to the left of the central spool of the valve and by way of port 18 and passage 12 to the rear end of the piston 4 to cause a forward movement thereof. Simultaneously the front end of the cylinder is connected with the exhaust by way of passage 11, port 17, and exhaust passage 26. The piston 4 will accordingly move forwardly and during its forward movement will first open the port 23 admitting live pressure fluid from the rear end of the cylinder to the forward end of the valve 28. Accordingly the valve will be thrown to the left and during normal operation of the motor the passage 11 will then be connected to a source of fluid supply and the passage 12 connected to exhaust and the movement of the piston 4 reversed. lVh'en the drill steel is stuck or cramped in the hole and it is desired to remove or loosen the bit from the hole the drilling mechanism is fed rearwardly in any well known manner. At this time the drill steel moves out of the range of the striking bar 5 of the piston, as shown in Fig. 3, and the piston increases its stroke entering the cushioning space 25 at the forward end of the cylinder a substantial. distance causing the pressure fluid therein to be highly compressed. This compressed fluid enters the restricted passage 37 and forces the auxiliary valve 40 upwardly from the position shown in Fig. 1 substantially to the position shown in Fig. 2 thereby connecting the passage 44 with the restricted passage 45" partially open ing the latter. At the completion of the forward piston stroke the compressed fluid in the front cushioning space acts expansively, thereby causing the piston to move rearwardly from the position shown in Fig. 2. When the passage 11 is uncovered by the piston pressure fluid flows through this passage to the forward end of the cylinder and acts on the forward piston area. As the piston moves rearwardly the port 24 is uncovered by the piston admitting live fluid to the throwing passage 22 and consequently the valve is thrown from the position shown in Fig. 2 to the position shown in Fig. 1. When the valve assumes this latter position live fluid flows through passage 45, thus allowing an auxiliary supply of live pressure fluid to pass from the supply passage 35 to the throwing passage 21 giving the latter a preliminary filling during the return piston stroke and prior to the admission of throwing pressure through the port- 23 and the throwing action thereof on the right hand end of the valve. This causes the reverse or throwing movement of the valve to be accelerated when the port 23 is opened during the succeeding forward piston stroke and consequently accelerating the time of admission of motive fluid through the passage 11, thus retarding the hammer piston and preventing the latter from excessively hammering the front cylinder head during withdrawal of the steel and consequently eliminating resultant breakage of the motor parts. It will herein be noted that due to the restricted size of the passage 87 the pressure below the auxiliary valve 89 is substantially constant and the valve is thus maintained open constantly during the withdrawal operation of the steel. hen normal drilling is resumed the striking bar of the piston again engages the shank of the drill steel and'the movement of the piston within the cushioning space 25 is substantially reduced consequently causing a resultant drop in pressure within the cushioning space and below the valve 39 causing the latter to again resume its closed or inoperative position as shown in Fig. 1.

Cooperating with my improved auxiliary valve 39 is improved hole cleansing means for the drill steel 6 which is made hollow in a usual manner. Disposed coaxially with the bore 38 within which the valve 39 is disposed is a reduced bore 47 within which a stem 48 is disposed. The outer end of this stem is provided with an operating member or push button 49. Disposed within a bore 50 formed in the cylinder 2 is a coiled spring 51 which engages the push button L9 thus urging the latter into its inoperative position, a slot and pin connection 52 being provided for preventing a derangement of the parts.

In the operation of the improved hole cleansing means it will be observed that when it is desired to cleanse the drill hole the plunger 48 is depressed by the operator and the valve 39 forced into the position shown in Fig. 4 thus causing live pressure fluid to flow through the center of the valve to the widely opened passage 45 leading to the throwing passage 21, thus causing the valve 28 to be held in the position shown in Fig. 2, consequently causing pressure fluid to flow from the inlet passage to the right hand side of the central spool of the valve through the passage 7 and passage 11 to the forward end of the cylinder. This causes the piston 4 to be retracted and held against the rear cylinder head. then the piston assumes this position live pressure fluid flows from the forward end of the cylinder through the fines 5 in' the striking bar of the piston and consequently through the hollow drill steel to the drill hole, it being understood that the pressure fluid flowing through the passage l5 is of suflicient volume, due to the position of the auxiliary valve 89, to overcome the pressure within the throwing passage 22. Furthermore, the volume of air flowing through the passage to the right hand end of the valve is greater than the volume of air flowing past the right hand end of the valve and through the passage 26 to exhaust, thereby causing the pressure to build up in the front end of the valve chest.

While I have in this application specifically described one form which my invention may assume in practice, it will be understood that this form is shown for purposes of illustration and that the invention may be modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

WVhat I claim as new and desire to secure by Letters Patent is:

1. In a pressure fluid motor, a cylinder, a piston reciprocable therein, passages for distributing flui d to and from said cylinder, a valve controlling said distributing passages, means including a throwing passage for controlling said valve, and means comprising passages one of which communicates with said throwing passage, and an auxiliary valve for con trolling the same operable in response to pressure conditions in a part of said cylinder to effect a preliminary flow of live pressure fluid to said throwing passage prior to the throwing action thereof on said valve to advance the time of throwing of said valve andadmission to an end of said cylinder when excessive pressures are built up in said end.

52.- In a pressure fluid motor, a cylinder, a piston reciprocable therein, passages for dis tributing fluid to and from said cylinder, a valve controlling said distributing passages, means comprising a throwing passage for controlling said valve, and means comprising an auxiliary valve actuated by fluid within said cylinder for giving a preliminary filling of live pressure fluid to said throwing passage prior to the throwing action thereof on said valve to accelerate the throwing of said distributing valve, advancing admission to the cylinder and preventing excessive movement of the piston.

3. In a pressure fluid motor, a cylinder having a cushioning space, a piston reciprocable therein, passages for distributing fluid to and from said cylinder, a valve controlling said distribution passages, means comprising a throwing passage for controlling said valve, and means comprising an auxiliary valve op erated by the pressure within said cushioning space for giving a preliminary filling of live pressure fluid to said throwing passage prior to the throwing action thereof on said valve to accelerate the throwing of said distributing valve, advancing admission to the cylinder and preventing excessive movement of the piston.

4. In a fluid pressure motor, a cylinder, a piston reciprocable therein, passages for distributing fluid to and from said cylinder, a valve controlling said distributing passages, means comprising a plurality of throwing passages for normally controlling said valve, and means comprising a fluid actuated auxil iary valve for admitting a supply of live pressure fluid to one end of said valve prior to the normal admission of throwing pressure to one of said throwing passages to accelerate the throwing action of said valve in order to cause a more effective cushion for said piston.

5. In a pressure fluid motor, a cylinder, a piston reciprocable therein, passages for distributing fluid to and from said cylinder, a valve controlling said distributing passages, and means comprising an auxiliary valve and passages controlled thereby automatically operable to effect admission of pressure fluid to a surface of said valve through said last mentioned passages to vary the time of throwing of said valve upon the occurrence of excessive movement of said piston in one direction.

6. In a pressure fluid motor, a cylinder having a cushioning chamber and a piston reciprocable therein, passages for distributing fluid to and from said cylinder, a valve for controlling said distributing passages, and an auxiliary valve and passages controlled thereby, said auxiliary valve being automatically operable in response to the pressure in said cushioning chamber to effect admission of pressure fluid to a surface of said distributing valve through said last mentioned passages to vary the time of throwing thereof when excessive movement of said piston takes place in one direction.

7. In a pressure fluid motor, a cylinder, a piston reciprocable therein adapted to actuate a hollow drill steel, passages for distributing fluid to and from said cylinder, a valve controlling said distributing passages, means including a throwing passage for controlling said valve, means comprising an auxiliary valve for giving a preliminary filling of live pressure fluid to said throwing passage prior to the throwing action thereof on said valve to cause admission to the cylinder to provide a more effective cushion for the piston, and means associated with said auxiliary valve for eifecting a hole cleansing operation.

8. In a pressure fluid motor, a cylinder having a head and a cushioning chamber, a piston reciprocable in said cylinder adapted to actuate a hollow drill steel, passages for distributing fluid to and from said cylinder, a valve controlling said distributing passages, means comprising an auxiliary valve operated by the pressure within said cushioning chamber for admitting pressure fluid to a surface of said valve to cause advance of admission to the front end of the cylinder to prevent said piston from excessively striking said head, and means associated with said auxiliary valve for effecting a hole cleansing operation.

9. In a pressure fluid motor, a cylinder, a piston reciprocable therein, passages for distributing fluid to and from said cylinder, a valve controlling said distributing passages, means comprising an auxiliary fluid actuated valve for preventing excessive movement of said piston in said cylinder, means controlled by said auxiliary valve for accelerating admission of pressure fluid to the forward end of the cylinder, and means associated with said auxiliary valve for eflecting a hole cleansing operation.

10. In a pressure fluid motor, a cylinder, a piston reciprocable therein, passages for distributing fluid to and from said cylinder, an automatic valve controlling said distributing passages, piston controlled pressure fluid means for controlling said valve, and means automatically responsive to abnormal cylinder pressure in a portion of said cylinder for varying the fluid pressure which controls said valve to change the timing of said valve.

In testimony whereof I aflix my signature.

THORE R. E. RUNDQVIST. 

